The present invention relates to a disk member and cone member in direct contact with one another with variable relative positioning providing a transmission with a finitely and variable ratio of input to output speed.
Gear ratios of vehicles are generally fixed to limited numbers of gears. These gears try to establish an ideal relationship between the input force of the motor and the speed of motion of the vehicle. Thus, at lower speeds, higher torque is applied to the driving axle while maximum speed is low; and at higher speed less torque is required but maximum speed is high. Maximum engine torque is usually constant while driving torque requirements vary greatly with speed and road topology. Ideally, a continuous gear shifting would optimize driving conditions. Today""s standard automobile transmissions generally provide 3 to 5 gear ratios and are manufactured with many parts. Road topology, frequent shifting of gears, many parts within all tend to provide high maintenance and non-optimal driving performance.
U.S. Pat. No. 3,747,424 describes a speed reducing gear having a frustoconical body acting as the reducing mechanism driving a horizontal output shaft. A horizontally engaged input drive shaft (worm gear) can be moved along the gradiated surface of the frustoconical body to reduce the speed ratio between the input and output. The invention requires a 90 degree angle between the input and output shafts making it awkward for a transmission shaft. It also requires a worm type interface for force transfer because the contact area of input to output would be very slight without a worm interface. It is also designed as a speed reducer.
U.S. Pat. No. 5,525,119 discloses a mechanism for varying rotational speed between two rotary shafts. It employs an intermediate roller contacting two cones. Speed variation is employed by the position of the roller between the two oppositely mounted cones while the roller is under pressure against the surfaces of both cones.
U.S. Pat. No. 4,161,890 discloses an improvement to the contact surfaces in preventing slippage between two substantially inelastic members that are in frictional engagement.
U.S. Pat. No. 4,183,253 discloses a moveable power transfer wheel interconnecting a pair of dual cones. Movement of the transfer wheel between both sets of cones varies input/output speed ratio.
What is needed is a mechanism employing direct drive means while able to vary the input/output speed ratio with no intermediate contacting parts. What is also needed is a mechanism to have the transfer of power directly between an input and an output member.
The present invention resolves these problems. The present invention provides an ability to vary speed directly between two members while providing direct power transfer with no intermediate parts. The present invention also provides in-line drive. That is, the input shaft and output shaft can be maintained with their individual axis in a coplanar relationship. The present invention is also simple to manufacture with minimal parts. The present invention is also easily adjustable and maintainable.
The main aspect of the present invention is to provide a continuously variable speed (within set limits) between a driving shaft and a transmitting output shaft.
Another aspect of the present invention is to provide a means for input and output drive contacting surfaces to be in parallel for optimal power transfer.
Another aspect of the present invention is to provide contact between both the driving member and the transmitting member in a co-linear fashion. That is, both members have outer surfaces that are maintained in parallel.
Another aspect of the present invention is to provide a means of adjustment of the speeds. An axially moveable shaft coupled to the disk shaped member in a reciprocating fashion accomplishes this. Movement of the disk shaped member surface to various parts of the cone surface changes the speed ratio.
Another aspect of the present invention is to provide a means for insuring constant pressure between the surface of the disk member and the cone member during operation. Constant pressure and high frictional coefficients prevent slippage during operation.
Another aspect of the present invention is to provide a high coefficient of friction between the disk member and cone member when in operation.
Another aspect of the present invention is to provide a means of having the input and output drives along the same plane for ease of assembly in using applications such as automobiles for example.
Another aspect of the present invention is ease of manufacture via fewer parts than a standard transmission.
Another aspect of the present invention is improved reliability and life via fewer parts and fewer wear surfaces than a standard transmission.
Another aspect of the present invention is ease of maintainability.
Variable speed is accomplished by moving a disk shaped member along a conical shaped member. In this description of the present invention the cone will be referenced as the input driving-member and the disk as the output-driving member. The input driving member, or cone, is connected to a shaft that is driven by a motor input such as an automobile engine. Both members are directly connected to input and output-drive shafts respectively and rotate along the axis of each shaft. Both members are in direct pressure contact with each other with no intermediate parts; thus power is transferred directly between the disk and cone members. The outer edge surface of the disk is parallel with the outer edge surface of the cone. A 1:1 speed ratio, for example, can be maintained when the output disk member circumference is at the large end of the input cone member with matching circumference. With the output drive shaft connected to the disk member and the input shaft connected to the cone member, the ratio would be 1:1. If the disk were moved to the smaller circumference (1/10th circumference of disk for example) end of the drive cone the ratio would be 10:1. More torque would be transmitted at the lower ratio. Selection of ratios would be a design requirement dependent and changeable via maximum and minimum circumferences of the cone.
Movement of a positioner shaft connected to the disk member accomplishes variable output speed changes. This movement adjusts the surface contact point between the disk member and the cone member. This provides a different surface contact point between the disk shaped member and the cone shaped member. The different surface contact point of the disk outer surface onto the cone outer surface is related to a different outside circumference of the cone member and thus a different drive ratio. The outside edge surface of the disk member is parallel to the outside longitudinal edge surface of the cone member. Movement and retention of position could be accomplished, for example, by an electrically driven screw shaft or by a hydraulic system to provide infinitesimal adjustment while also providing direct lateral holding power.
Constant pressure between the disk member and the cone member contact points can be maintained with various design methods. Shown herein is a method using a system with a pivot point hinge that places a downward pressure on the output shaft by means of a lever arm, adjustable spring and cams. Pressure over the range of movement of the contact surface points between the disk and cone members is thus both constant and can be easily adjusted based on design requirements.
A high coefficient of friction can be maintained between the outer surface of the cone member and the outer surface of the disk member with modern materials that provide a high frictional coefficient while exhibiting relatively little wear. The working cone member is presently flame sprayed with stainless steel onto the steel base. Other materials such as specially developed ceramics, kevlar, carbide impregnated materials etc. also may be desirable depending on the application. Disk member outside edge thickness design variation also provides a design means of increasing or decreasing contact surfaces between the disk and cone member surfaces.
While the output and positioner adjustment shafts are parallel, all shafts (input, output and positioner) are all co-planar. This is accomplished by a housing design with bearings, clamps and framework holding all shafts within the same co-plane. This lends itself to ease of assembly and application.
Other aspects of this invention will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.